A car of mass 900 kg travels along a level road at 20 m/s.
The driver applies the brakes and the car stops.
Calculate the kinetic energy of the car before the brakes are applied.
Describe the energy transfers that take place as the car slows down and stops.
The Table shows the kinetic energy of the car at different speeds.
Table
| Speed in m/s\text{m/s}m/s | Kinetic energy in J\text{J}J |
|---|---|
| 10 | 45 00045\,00045000 |
| 15 | 101 250101\,250101250 |
| 30 |
Calculate the missing value in the Table.
The car makes one emergency stop from 10 m/s and another from 30 m/s.
Use data from the Table to explain why the brakes become much hotter when the car stops from 30 m/s.